When adjusting a Subaru timing belt, be sure to replace the belt after 105,000 miles; the vehicle's water pump should also be replaced at the same time. Also, oil shortens the life of a timing belt, and the mechanics of Subaru's interference motor means that only experienced mechanics should work on the belt tensioners.
An investment in specialty timing belt adjustment tools is recommended; otherwise adjustments can be made using standard shop tools such as a 12mm Allen wrench. Break the front crankshaft pulley free from the engine case either using the purpose-built Kent Moore tool or a 22m socket crank bolt. It can be helpful to place something over the transmission cooler lines to keep them protected. Also, remove the battery before operating on the car.
After this step, break the cam gear bolts loose. This step can be performed after removing the timing belt for inspection, but it is best done before. Be sure to clip the belt so that it does not jump when the bolts are broken free. It can be helpful to replace the cam seals if problems are discovered with the timing belt.
It can be helpful to compress the timing belt's hydraulic tensioner during the adjustment procedure. Fit the tensioner in a bench vise, and slowly compress it, waiting for a tension release after each turn of the vise. Once it is compressed, slide through the lock pinhole with a long, thin Allen wrench.